Key Items in Devil May Cry

Devil May Cry has a large amount of Key Items which Dante must find and use to progress through the game.

Rusty Key
Rusty Keys are old but functioning keys found throughout Mallet Castle and are used to unlock certain doors. There are three of them in Devil May Cry:
 * 1) The first key is found in the first mission in the hand of a seemingly lifeless puppet within the gatekeeper's room and is used to open the door to the hangar.
 * 2) The second key is found in Mission 2 embedded in the painting of a Grim Reaper within the library and is used to open the door to the courtyard.
 * 3) The final key is found within a pipe in the waterways in Mission 6, and is used to open a door further along them.

Staff of Judgment

 * A mysterious ornamental staff found in Mallet Castle that is required to open the Judge of Death door. It cannot be used as a weapon. It is found in Mission 2.

Pride of Lion

 * A somewhat sacred seal that allows passage through the Lion's Door. (Shadow) It is found in Mission 3: Destroyer of Ardor.

Death Sentence & Melancholy Soul
Both key items are found in Mission 4.
 * The Death Sentence is an extremely decorative sword that is said to be used for rituals, although its only in-game function is to act as a key to retrieve the Melancholy Soul from the Melancholy bust. It cannot be wielded.
 * A strange ornament that is described to look like a soul, although it merely looks like a brownish-reddish ball with speckles. It acts as the key into the Mallet Sewers, although it must be inserted into the door quickly, or else it will lose its power.

Guiding Light

 * A literal key to unlocking the sun door in Mallet Castle that leads to an unholy ritual chamber holding a Divinity Statue. It must be inserted quickly into the sun door however, or it will slowly kill Dante. It is found in Mission 6.

Trident

 * A decorative pike that is the symbol of a god, used as a key to unlocking the iron wrought gate in Mallet Castle. It cannot be used as a weapon. The Trident is found on the roof of the mansion in Mission 8 after defeating Phantom.

Sign of Chastity & Chalice
Both key items are found in ''Mission 11.
 * A taxidermic organ coated in a strange crystal, it acts as a key to unlocking the safeguard to the Chalice. It most closely resembles a brain.
 * A seemingly sacred goblet that apparently held the blood of important mythological deities who were sometimes referred to as the "divine dead".

Staff of Hermes
The Staff of Hermes is found in Mission 13, but isn't used until Mission 16, where it activates the portals to the Mirror World.
 * The symbol of a messenger god often used to represent alchemy, it acts as a key to opening two magical mirrors. It cannot be used as a weapon.

Emblem Shield & Pair of Lances
The Emblem Shield is discovered in Mission 14, and used in Mission 15. The Pair of Lances are found and used in Mission 15.
 * A small shield donning the insignia of a skull, it acts as a key to unlocking two doors: one leads to the Pair of Lances, and the other leads to the hidden Fire Arm, Nightmare Beta. The Emblem shield is one of the few key items that can be used more than once.
 * A pair of small, but heavy-looking javelins held by the knight statues on the coliseum double doors which allow passage into the sacrificial grounds. They cannot be wielded as weapons.

Luminite
Luminite is an ordinary Underworld stone that has become fluorescent when brought to the Human World. It can be found during Mission 15: Wheel of Destiny, in a pile of rubble blocking the corridor surrounding the Coliseum, and it must be obtained in order to open the doors of the lower corridors containing the Pair of Lances and the Nightmare-β.

Wheel of Destiny
A round, metal plate with engraving that represents destiny. Required to re-lower the drawbridge of Mallet Castle. Obtaining it at the end of Mission 15 ends the mission. It is used at the beginning of Mission 16 to lower the drawbridge and re-enter the castle.

Quicksilver
A clear, crystal ball filled with mercury, or quicksilver. Needed to unlock the door to the Castellan's Throne Room. It is found in Mission 17.

Philosopher's Egg & Elixir
The Philosopher's Egg is found in Mission 18, and it is transformed into the Elixir after a fight with Nightmare. The Elixir is then used to enter the Mirror World in the Castellan's Bedroom.

Philosopher's Stone
A mysterious geometric stone covered with alchemy-related engravings. It is found in Mission 19 and is eeded to open the Mouth of the Underworld.